This study presents a generic methodology to produce simplified models able to provide a comprehensive life cycle impact assessment of energy pathways. The methodology relies on the application of global sensitivity analysis to identify key parameters explaining the impact variability of systems over their life cycle. Simplified models are built upon the identification of such key parameters. The methodology is applied to one energy pathway: onshore wind turbines of medium size considering a large sample of possible configurations representative of European conditions. Among several technological, geographical, and methodological parameters, we identified the turbine load factor and the wind turbine lifetime as the most influent parameters. Greenhouse Gas (GHG) performances have been plotted as a function of these key parameters identified. Using these curves, GHG performances of a specific wind turbine can be estimated, thus avoiding the undertaking of an extensive Life Cycle Assessment (LCA). This methodology should be useful for decisions makers, providing them a robust but simple support tool for assessing the environmental performance of energy systems.

Keywords:energy environmental impact industrial ecology life cycle assessment (LCA) meta-analysis regression SummaryA full life cycle assessment (LCA) is usually a time, energy, and data-intensive process requiring sophisticated methodology. Our meta-analysis of life cycle greenhouse gas (GHG) emissions of wind electricity highlights several key, sensitive parameters to provide a better understanding of the variability in LCA results, and then proposes a methodology to establish a simplified, streamlined approach based on regressions built on these key parameters. Wind electricity's environmental performance can be linked to three essential components: technological (e.g., manufacturing), geographical (e.g., wind speed), and LCA methodology (e.g., product lifetime).A regression has been derived based on detailed LCA results from a representative sample of 17 industrial wind turbines manufactured and recently installed in Europe on average land configurations. Simple GHG performance (i.e., emissions) curves depending on average on-site wind speed and wind turbine lifetime are proposed. Whatever the system power, considering the full range of possible wind speeds in Europe (4 to 9 meters per second [m/s]) and a lifetime of 10 to 30 years, emissions vary from 8.7 to 76.7 grams of carbon dioxide equivalent per kilowatt-hour (g CO 2 -eq/kWh) when the wind speed is less than 6.5 m/s, and from 4.5 to 22.2 g CO 2 -eq/kWh when the wind speed is 6.5 m/s or greater. This second situation with a turbine lifetime of 20 years is assumed to be most realistic based on economic criteria.This research presents simplified models as an alternative to detailed LCA. The methodology has been applied as a first trial to wind electricity and could be applied to other energy pathways.

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